## Ports {#ports}

### Darwin {#darwin}

<!-- go.dev/issue/64207 -->
As [announced](go1.22#darwin) in the Go 1.22 release notes,
Go 1.23 requires macOS 11 Big Sur or later;
support for previous versions has been discontinued.

### Wasm {#wasm}

<!-- go.dev/issue/63718 -->
The `go_wasip1_wasm_exec` script in `GOROOT/misc/wasm` has dropped support

    id: error-handling-proposal
    attributes:
      label: Does this affect error handling?
      description: If so, how does this differ from previous error handling proposals?
      placeholder: |
       Yes or No

       If yes, 
        1.how does this differ from previous error handling proposals?

    validations:
      required: true

  - type: textarea
    id: generics-proposal
    attributes:

// The zero value for Reader operates like a Reader of an empty slice.
type Reader struct {
	s        []byte
	i        int64 // current reading index
	prevRune int   // index of previous rune; or < 0
}

// Len returns the number of bytes of the unread portion of the
// slice.
func (r *Reader) Len() int {
	if r.i >= int64(len(r.s)) {
		return 0
	}
	return int(int64(len(r.s)) - r.i)
}

[`filepath.EvalSymlinks`](/pkg/path/filepath#EvalSymlinks) no longer evaluates
mount points, which was a source of many inconsistencies and bugs.
At previous versions (`winsymlink=0`), mount points are treated as symlinks,
and other reparse points with non-default [`os.ModeType`](/pkg/os#ModeType) bits
(such as [`os.ModeDir`](/pkg/os#ModeDir)) do not have the `ModeIrregular` bit set.

For Go 1.23, it defaults to `winsymlink=1`.
Previous versions default to `winsymlink=0`.

On Windows, [EvalSymlinks] no longer tries to normalize
volumes to drive letters, which was not always even possible.
This behavior is controlled by the `winreadlinkvolume` setting.
For Go 1.23, it defaults to `winreadlinkvolume=1`.

	if b.lastRead <= opInvalid {
		return errors.New("bytes.Buffer: UnreadRune: previous operation was not a successful ReadRune")
	}
	if b.off >= int(b.lastRead) {
		b.off -= int(b.lastRead)
	}
	b.lastRead = opInvalid
	return nil
}

var errUnreadByte = errors.New("bytes.Buffer: UnreadByte: previous operation was not a successful read")

On Windows, [Readlink] no longer tries to normalize volumes
to drive letters, which was not always even possible.
This behavior is controlled by the `winreadlinkvolume` setting.
For Go 1.23, it defaults to `winreadlinkvolume=1`.

	MOVQ DR7, SI // 0f21fe
	// Test other movtab entries.
	PUSHQ GS // 0fa8
	PUSHQ FS // 0fa0
	POPQ FS  // 0fa1
	POPQ GS  // 0fa9
	// All instructions below semantically have unsigned operands,
	// but previous assembler permitted negative arguments.
	// This behavior is preserved for compatibility reasons.
	VPSHUFD $-79, X7, X7         // c5f970ffb1
	RORXL $-1, (AX), DX          // c4e37bf010ff

first preceding non-empty expression list and its type if any.
Omitting the list of expressions is therefore equivalent to
repeating the previous list.  The number of identifiers must be equal
to the number of expressions in the previous list.
Together with the <a href="#Iota"><code>iota</code> constant generator</a>
this mechanism permits light-weight declaration of sequential values:
</p>

<pre>

	}
}

type writeErrorOnlyWriter struct{}

func (w writeErrorOnlyWriter) Write(p []byte) (n int, err error) {
	return 0, errors.New("writeErrorOnlyWriter error")
}

// Ensure that previous Write errors are immediately returned
// on any ReadFrom. See golang.org/issue/35194.
func TestWriterReadFromMustReturnUnderlyingError(t *testing.T) {
	var wr = NewWriter(writeErrorOnlyWriter{})
	s := "test1"